1. Field of the Invention
It is related to a temperature measuring device for a semiconductor manufacturing apparatus, which measures the temperature of a semiconductor wafer in a process of manufacturing a semiconductor device (an LSI: a large scale integrated circuit); a method of measuring temperature, by using the temperature measuring device, in the semiconductor manufacturing apparatus; and a semiconductor manufacturing apparatus which measures temperature by using the temperature measuring device.
2. Description of the Prior Art
In processing for manufacturing a semiconductor device (an LSI), there are a number of processes for heating a semiconductor wafer, such as a film forming process, an impurity diffusion process and an etching process. In these processes, the temperature of the wafer needs to be strictly managed. For example, in the chemical vapor deposition (CVD) process at the time of forming a film, large unevenness is caused in the film thickness if the temperature of the wafer is not strictly managed. In addition, in the etching process at the time of forming a wiring, a defect, such as an increase in the wiring resistance, a short circuit, or disconnection, is caused if the temperature of the wafer is not strictly managed.
In a case of a heating furnace, and a film forming apparatus such as a CVD apparatus used in the impurity diffusion process, the temperature is managed by monitoring the temperature in the apparatus, by use of a thermocouple arranged in the apparatus. However, in an apparatus of this kind, temperature on a wafer surface is not directly measured. For this reason, the temperature is not managed at a sufficiently strict level. In addition, the thermocouple arranged in the apparatus cannot measure the distribution of the temperature on the wafer surface.
In a single wafer apparatus used in the etching process or the physical vapor deposition (PVD) process, the ultimate temperature on a wafer surface is measured by attaching, to the wafer surface, a film, such as TEMP-PLATE (registered trademark), including an element which changes the color thereof according to the temperature. In the case of the temperature measurement using TEMP-Plate, it is possible to determine whether or not the ultimate temperature reaches a desired temperature, but not to know the temporal change in the temperature.
In order to solve such a problem, Publications of Japanese Patent Applications No. Sho 62-139339 (Patent Literature 1), No. Hei 11-118616 (Patent Literature 2), and No. 2002-16117 (Patent Literature 3) disclose that a thermocouple is formed on a semiconductor wafer, and that the temperature on a wafer surface is measured by the thermocouple.
Patent Literature 1 discloses that the thermocouple is formed on the wafer, but does not disclose how an output of the thermocouple is connected to a measuring device (a measuring circuit). A method may be employed in which one end of a cable of the measuring device is directly connected to an electrode on the wafer. This method, however, has a disadvantage that it is troublesome to connect the cable and to remove the cable after use. In addition, when the wafer is placed inside a vacuum chamber, it is difficult to take out the other end of the cable to the outside of the chamber.
Patent Literature 2 discloses that a thermocouple formed on a wafer and an external measuring device are connected to each other via a connector. In this case, however, an operator needs to attach or detach the connector, and this is also troublesome. As in the case of Patent Literature 1, a wafer is placed in a vacuum chamber, this method also has a disadvantage that it is difficult to take out one end of a cable to the outside of the chamber.
Patent Literature 3 discloses that an output of a thermocouple is taken out to the outside via an electrode pad provided in an edge portion (a vicinity of an orientation flat) of the wafer. However, Patent Literature 3 does not disclose how the electrode pad is connected to the measurement instrument.
In general, a semiconductor wafer is conveyed to a semiconductor manufacturing apparatuses (such as a film forming apparatus, an etching apparatus, and a heating furnace), and is set in a predetermined position by an automatic conveyor device. For this reason, there is a demand for a temperature measuring device which is conveyed and automatically set in semiconductor manufacturing apparatuses in a manner similar to that of a normal semiconductor wafer, and which can measure the temperature under a condition similar to a condition where the wafer is actually processed.